Silencers also fall within the scope of the Pressure Equipment Directive (PED) when the operating pressure is greater than 0,5 bar. Discharge silencers are designed in round form, typically 3 – 10 mm thick and ideally with dished ends. An air pressure test is recommended on account of the interior fittings. The acoustic interior fittings can be produced as a circumferential baffle with an absorptive core. Both pressure and temperature have to be taken into consideration when designing the silencer.